The waving or straightening of hair is a well established and well developed art in which substantial attention has been directed to improve the present level of technology. Although substantial changes have occurred throughout the last decades, various problems continue to plague the industry in spite of numerous attempts to reduce or eliminate these problems.
In order to best understand the present state of the art and the problems existing therein, it is important to reiterate that hair fibers are composed of a unique protein called “keratin” which is distinguished by the fact that it contains a very significant amount of an amino acid (cystine) which contains the element sulfur in addition to the elements nitrogen, oxygen, carbon and hydrogen. In the natural biosynthesis of hair, the element sulfur covalently links intra or inter polypeptide chains (K) through two sulfur atoms (S—S) to give keratin protein (K—S—S—K). Only by chemical action can this covalent linkage be broken.
Since these disulfide bonds are relatively strong bonds and are not affected by water, permanent results are obtained by altering the disulfide bonds through cleavage and recombination. In this way, a permanent configuration change of the hair is attained. However, chemical action is required in order for this disulfide linkage to be broken. In this regard, many prior art compositions have been developed for the cold permanent waving of hair. Typically, these prior art systems treat the hair with reducing agents which break the disulfide (cystine) linkage in the hair, while the hair is wound around a curling rod.
In general, permanent hair waving is usually carried out by subjecting the hair to reagents containing a free —SH group or thiol. These materials are also called mercaptans. In this treatment, the hair usually is either wrapped on the rods with water or the lotion containing the thiol, and then saturated with thiol lotion. The thiol waving agent acts to break the disulfide bonds within the hair fiber forming thiol groups in the hair protein and disulfide bonds between two thiol waving agent molecules.
In addition to the waving of hair using the organic thiol compounds, substantial effort has been expended in waving or straightening hair using aqueous alcoholic ammonia and non-alkali metal bisulfites and sulfites without an oxidative fixative treatment. The chemistry employed for waving and straightening hair using bisulfite and sulfite compounds is very different from the use of thiols.
In this regard, the chemical reaction (1) of bisulfite with SS bonds of hair, as shown below, can produce equal bunte salts (KSSO3) and Cysteine residues (KSH). In addition, hydrogen bonds and salt linkages in hair are also cleaved with the bisulfite solutions. The prior known processes use acidic hydrogen peroxide solutions shown by chemical reaction (2) to reform the disulfide SS bonds from the cleaved cysteine residues.KSSK+HSO3→KSSO3+KSH  (1)KSH+½H2O2→KSSK+H2O  (2)
In these reactions, the acidic hydrogen peroxide has no effect on the bunte salt and therefore no disulfide bonds are reformed. This implies that a maximum of 50% of the original SS broken bonds may not be recovered and will result into hair damage and weak curl formation. The composition disclosed in U.S. Pat. No. 5,775,342 uses premixed alkaline hydrogen peroxide solutions of 1.80-2.20% by weight and pH of 8.50-9.20 to cleave the bunte salt shown in chemical reaction (3) to form SS disulfide bonds. Thus the alkaline hydrogen peroxide solution produces a more efficient “lock in” set, however with excessive hair surface damage and hair color lightening due to oxidation of melanin. Furthermore higher oxidation products in hair can occur under these conditions such as cysteic acid in chemical reaction (4)KSSO3+OH→KSH+SO4+H2O2—KSSK+H2O  (3)KSSK+H2O2→KSO3+H2O  (4)
Although numerous prior art products have been developed based upon the use of bisulfites and sulfites, these prior art systems have been found to be deficient in satisfying all of the needs and desires of users. In particular, these prior art compositions suffer from slow diffusion of actives into the cortex of hair fibers and slow reaction rates with hair. These factors typically result in poor overall wave performance. Furthermore, the prior art compositions typically bleach the natural color of hair, produce excessive hair damage, and leave an unpleasant malodor residue in hair.
Therefore, it is a principal object of the present invention to provide a composition and a method of use for waving or straightening hair fibers which is capable of imparting a longer-lasting hair set, while completely eliminating the need for applying an oxidizing or neutralizing agent.
Another object of the present invention is to provide a hair waving/straightening composition and method of use having the characteristic features described above which is capable of improving the physical properties of the treated hair, such as a shine, luster, softness, manageability, hair body and thickness.
Another object of the present invention is to provide a hair waving/straightening composition and method of use having the characteristic features described above which substantially reduces or eliminates damage to the hair fibers while also substantially reducing or eliminating bleaching of the natural color of hair.
Another object of the present invention is to provide a hair waving/straightening composition and method of use having the characteristic features described above which virtually eliminates any residual unpleasant malodor on hair fibers, as well as providing an efficient system where actives rapidly diffuse into the hair fibers while providing rapid reaction rates with the hair fibers.
Other and more specific objects will in part be obvious and will in part appear hereinafter.